Generally, the manufacturing process of the semiconductor device comprises the steps of: i) forming the pattern of photoresist on the conducting layer formed on the semiconductor substrate, and ii) forming the pattern of conducting layer using said pattern as a mask. The pattern of photoresist used as said mask has to be removed by the photoresist stripper on the conducting layer in the cleaning process followed after the forming process of said pattern of conducting layer. However, it is difficult to remove the photoresist in the following cleaning process because the dry etching is used as the lithography of conducting layer for forming the pattern of conducting layer in the manufacturing process of the semiconductor device recently.
The dry etching process replaces the wet etching process using the acidic liquid chemicals and performs the etching process by using the reaction of gas phase-solid phase between plasma gas and material layer like conducting layer. The dry etching process is the mainstream of etching process due to the ease of control and the formation of a sharp pattern recently. There are many kinds of dry etching, but it is difficult to remove the photoresist because the ion and radical in the plasma gas react with said photoresist film complicatedly on the surface of photoresist film in the etching process of conducting layer which makes the photoresist film thermoset rapidly. If the reactive ion etching (RIE) is used as an example of dry etching, it is difficult to remove the photoresist by using the current photoresist stripper with reproducibility.
Another example of the process which makes it difficult to remove the photoresist is ion implantation. In the manufacturing process of the semiconductor device, it is the diffusing process of the atoms such as P, As, B, etc. onto the certain area of silicon wafer to give the conductivity. In the ion implantation process, said ions are implanted onto the area of silicon wafer uncovered by the photoresist pattern, but at the same time, the surface of the photoresist pattern used as a mask during the process is denatured through the surface chemical reaction with the accelerated ion beams. Therefore, it is difficult to remove the photoresist film after the ion implantation process by using any solvent in the cleaning process.
The photoresist film after said dry etching or ion implantation process cannot be removed completely by using the current photoresist strippers. Although being removed, it is difficult to perform the cleaning process stably because it needs severe conditions such as high temperature over 100° C. and long dipping time. So, it increases the defect rate of the semiconductor device.
On the other hand, currently suggested photoresist stripper composition consisting of alkanol amine and diethyleneglycol monoalkyl ether has been used generally due to weak smell, low toxicity and efficient removal ability for the most photoresist films. However, said stripper composition is known not to able to sufficiently remove the photoresist film exposed to the plasma gas or ion beams during the process of dry etching or ion implantation process. Therefore, the development of new photoresist stripper composition is strongly required to remove the photoresist film denatured via the dry etching and ion implantation processes.
As described above, it is difficult to remove the photoresist film by using the photoresist stripper after ion implantation. Especially, it is more difficult to remove the photoresist film treated with the high dose of ion implantation to form the source/drain area in the manufacturing of very large scale integrated circuit (VLSI). During the ion implantation process, the surface of the photoresist film is thermoset by the reaction heat originating from the high dose of ion and the ion beams having the high energy. The semiconductor wafer is usually heated at the high temperature above 200° C. during the ashing process. At that time, the residual solvent inside the photoresist should be removed as a vapor, but it is impossible due to the thermoset layer formed on the surface of the photoresist after the high dose of ion implantation.
Further, as the pressure inside the photoresist film grows up in the ashing process, the surface of the photoresist film is ruptured by the residual solvent, which is called ‘popping’. The surface thermoset layer scattered by popping forms fine dusts which are difficult to be removed. Because the said thermoset layer of photoresist surface is formed by the heat, the impurity ion, dopant, is substituted into the molecular structure of the photoresist to yield a crosslinking which is oxidized by O2 plasma. The oxidized photoresist film forms fine dusts and particles which are the source of contamination and give decrease of production rate in the manufacturing of very large scale integrated circuit (VLSI).
As the photoresist stripper composition used in current wet cleaning process, the photoresist stripper composition prepared by mixing organic amine compound and many kinds of organic solvent is suggested. Especially, the photoresist stripper composition comprising monoethanolamine (MEA) as a necessary component among organic amine compounds is generally being used. However, the photoresist stripper comprising a small amount of deionized water still has a problem of pit formation on the bottom metallic wiring due to the reaction between amine and deionized water in the rinsing process.
In the manufacturing process of the semiconductor device recently, the condition of the process is so severe, for example, each device like silicon wafer is treated at high temperature of 110˜140° C., that the photoresist often is baked at high temperature. But, said photoresist stripper cannot remove the photoresist baked at high temperature sufficiently. The photoresist stripper composition comprising water and/or hydroxylamine compound is disclosed as the composition for removing said photoresist baked at high temperature (Japanese laid-open patent publication 4-289866; Japanese laid-open patent publication 6-266119; Japanese laid-open patent publication 7-69618; Japanese laid-open patent publication 8-262746; Japanese laid-open patent publication 9-152721; Japanese laid-open patent publication 9-96911).
However, said photoresist stripper composition also cannot remove the photoresist film thermoset by dry etching, ashing and ion implantation and the photoresist film denatured by metallic by-product etched from the bottom metallic film in the said process sufficiently. Particularly, said photoresist stripper composition is not effective for removing denatured photoresist film produced at the sidewall of pattern if new metallic film is used, or new insulating material is used as an insulating film between layers in the process.
Further, the photoresist stripper composition using organic solvent as a main solvent has been used until now. But, the organic solvent is harmful environmentally and needs a high preparation cost.
On the other hand, the photoresist stripper composition comprising hydrazine hydrate as an antioxidant and water as a main solvent or cosolvent is disclosed (Korean laid-open patent publication 2003-0025521; Japanese laid-open patent publication 2002-196509). While the environment-friendly aspect of said composition is improved due to the high content of water compared to current photoresist stripper, if the content of water is more than 40%, the solubility of photoresist is decreased. Because of the low removal ability of photoresist, the application of said composition is limited.
The present inventors found that if the photoresist stripper composition comprising more than 40 wt % of water and hydrazine hydrate or amine compound and polar solvent contains the corrosion inhibitor selected from the group consisting of imidazoline derivative, sulfide derivative, sulfoxide derivative, aromatic compound or aromatic compound with hydroxyl group and monoalcohol compound of C2˜C10, the reaction time and the corrosion of the bottom film is reduced remarkably in the removing process of thermoset or denatured photoresist.